Electromagnetic switch



y 1938- w. FONDILLER 2,115,804

ELECTROMAGNETIC SWITCH Filed Sept. 18, 1935 INVENTOR W FOND/LLER A 7' TORNEV Patented May 3, 1938 UNITED STATES PATENT OFFICE Telephone Laboratori es, Incorporated. New

York, N. Y., a corporation of New York Application September 4 Claim.

This invention relates to electrical switchins devices, and more particularly to electromagnets.

In numerous cases where electromagnets are used to open and close circuits, it is very impor- 5 tant to have the electromagnet as fastin its release as possible. This is particularly true in the case of electromagnets .used in automatic telephone exchange systems to effect the interconnection of telephone lines; for example, in the 19 so-called cross-bar type system.

The usual method of obtaining fast release characteristics in electromagnets is to increase the self-demagnetization factor of the magnetic circuit by means of air-gaps maintained between 15 the core and armature in the operated position.

This has the undesirable eiiect, however, of reducing materially the magnetic circuit eiiiciency with resultant increase in the-required number of ampere turns for operation.

It is the object of this invention tospeed up the release of electromagnets without materially affecting their operating efliciency, and this object I accomplish by introducing an auxiliary mag- I netic material, suchas compressed powdered mag- 25 netic material at a critical point or points in the magnetic circuit, such as on the contacting area of either the armature or the core. This compressed powdered magnetic material s a high degree of self demagnetization though its permeability is inferior to that of iron. The term iron'{ is here used in a generic sense and includes the high permeability alloys commonly used in electromagnets, such as silicon steel, permalloy, etc. The presence in the magnetic circuit of the 5 auxiliary magnetic material will not materially increase the reluctance of the magnetic circuit, but will be very effective in reducing its retenu m A In the illustrations, compressed powdered magi netic material is shown as the auxiliary material.

It should be understood, however, that other alloys having lower permeabillty'than iron can be used and will approximate the improvement in release characteristics obtained with the powdered material.

Referring to the drawing,

Fig. l is a perspective view of anassembled relay in which this invention is embodied;

Fig. 2 is a perspective view .of the armature and core with the powdered magnetic material located on the front end of the armature and the rear portionof the core;

. Fig. 3 is a perspective view of the armature and 55 corefwith the powdered magnetic material located 18, 1935, Serial No. 41,027

on the'front portion of the core and the rear of the armature:

Fig. 4 is a perspective view of another type of relay in which my invention is embodied; and

Fig. 5 is a perspective view of the armature and 5 core thereof.

The relay shown in Figs. 1, 2, and 3 of the drawing has the same mechanica'larrangemen-t as that shown in Patent 1,973,090 to D. D. Miller, issued September 11, 1934, and reference is made to that patent for a description of these details.

One embodiment of the invention is illustratedin detail in Figs. 1 and 2. As shown in these figures, the self-demagnetizing compressed powdered magnetic material takes the form of an insert llin the armature II where the armature is to make contact with the core I2 when the armature is attracted. The rear of the core where the armature rests onthe same is also provided with a similar insert i3. This insert i3 is pro 0 vided in the rear of the core due to the character of the magnetic circuit of this relay; that is, this relay is'provided with a closed magnetic circuit at its rear end and the insert is located at this I point to afford quick release of the armature. Since the compressed powdered magnetic material is brittle,-I prefer to so locate it that a strip of the armature metal surrounds the material. This I accomplish by compressing magnetic material and locating it in an aperture in the arma ture. In order to effect quicker release of the. armature, I preferably break the magnetic circuit at this point by saw cuts I4.

Referring now to Fig. 3, in the construction there shown, I have reversed the position of the inserts, the core insert is being near the front end of the core and the armature insert it at the rear of the armature, the magnetic circuit being broken adjacent the insert it.

Referring now to Figs. 4 and 5, the relay shown .40 in these figures has the same mechanical 61- V rangement as that shown inthe patent to E. B. Craft, No. 1,121,897,'of December 22, 1914, and reference is made to that patent for a description of these details. In this embodiment of the in-' 4 vention, the compressed powdered magnetic insert I1 is located on the core It at the point where armature l9 makes contact therewith.

What is claimed is:

1.- In an electromagnet, a core, a winding there- 60- on, a perforated armature, compressed powdered magnetic material ,in'the perforation in said armature and said armature being slit adjacent opposite sides of the powdered magnetic material to interpose a break in the magnetic circuit.

2. In an electromagnet, a core, a winding thereon, an armature, said core being provided with an indentation filled with compressed powdered magnetic material where said core engages the armat'ire.

3. In an electromagnet, a core, a winding thereon, an armature, a mounting plate, said armature being hinged thereto at its rear and resting thereat on aid core and having an aperture adjacent its rear'portion in which is located compressed powdered magnetic material, said armature having a free end spaced from a forward end of said core and to be attracted thereto, said core at its forward end being provided with compressed pow- 2,11s,a o4

dered magnetic material where it is engaged by the armature when said armature is attracted.

4. In an electromagnet, a core, a winding thereon, an armature having one end resting on an end portion of said core and a free end spaced from and to be brought into engagement with an opposite end portion of said core, said armature being provided at its free end where it is to engage the core with compressed powdered magnetic material, slight air-gaps being provided on both sides of said material, and said core being provided at the point upon which said armature rests with an insert of compressed powdered magnetic material.

WILLIAM FONDILLER. 

